adequacy

From J.I. Packer in Knowing God,

In other words, the first commandment God told Israel to serve him exclusively, not only because they owed it to him, but also because he was worthy of their entire and exclusive trust. They were to bow to his absolute authority over them on the basis of confidence in his complete adequacy for them. And, clearly, these two things needed to go together; for they could hardly have been wholehearted in serving him to the exclusion of other gods if they had doubted his all sufficiency to provide whatever they might need... (p. 268, emphasis mine).

...We are afraid of the consequences of going the whole way into the Christian life. We shrink from accepting burdens of responsibility for others because we fear we should not have the strength to bear them. We shrink from accepting a way of life in which we forfeit material security because we are afraid of being left stranded. We shrink from being meek because we are afraid that if we do not stand up for ourselves we shall be trodden down and victimized, and end up among life's casualties and failures. We shrink from breaking with social conventions in order to serve Christ because we fear that if we did, the established structure of our life would collapse all around us, leaving us without footing anywhere.

It is these half-conscious fears, this dread of insecurity, rather than any deliberate refusal to face the cost of following Christ, which makes us hold back. We feel that the risks of out-and-out discipleship are too great for us to take. In other words, we are not persuaded of the adequacy of God to provide for all the needs of those who launch out wholeheartedly on the deep sea of unconventional living in obedience to the call of Christ. Therefore, we feel obliged to break the first commandment just a little, by withdrawing a certain amount of our time and energy from serving God in order to serve mammon. This, at bottom, seems to be what is wrong with us. We are afraid to go all the way in accepting the authority of God, because of our secret uncertainty as to his adequacy to look after us if we do.

Now let us call a spade a spade. The name of the game we are playing is unbelief (pp.269-270, emphasis mine).